Investigating mortality in sheep and lambs exported through Adelaide and Portland

Summary

The objective of the LIVE.123 project was to determine the rate, causes and predisposing factors of mortality for live export sheep as well as the relative mortality risk for different lines of sheep. Approximately 1.65 million sheep in 24 shipments were tracked from farm of origin to port of discharge between September 2005 and June 2008. Salmonella induced enteritis was the most common cause of mortality (34.4%), followed by inanition (23.9%) and enteritis/inanition (18.2%).
Seventy-four percent of mortality was traced to 18% of lines. Pastoral sheep from NSW and Queensland sheep were found to have higher voyage mortality than other sheep. Other risk factors for mortality were age, ship and time of year. Factors identified as important drivers of disease were level of salmonella exposure and host immunity. The observation that specific lines of sheep from certain locations are more likely to die suggests that the immunity of sheep from these locations is compromised by property of origin factors or by the process involved in getting these animals to the assembly depot. Recommendations for reducing mortality include minimising salmonella challenge at the assembly depots, promoting consistent industry adoption of the road transport guidelines, avoid sourcing sheep from high risk locations pending clarification and correction of the risk posed to these sheep, implementation of a uniform information management system across industry to track sheep performance from origin to discharge, and improve the training and definition of responsibilities for shipboard veterinarians and stockmen.